GPS in lieu of DME

Pilot Hopeful said:
Interesting: When the IPH shows G1000 screenshots for flying the DME arc on the ILS7L approach at DAB, the database arc (i.e., the one loaded with the approach) is depicted! (See figures 7-19, 7-20, 7-21) There is no mention of needing to make OMN the active waypoint. Is this an oversight or evidence that a database arc is sufficient?
Click to expand...
Not only is it sufficient it is the ONLY GARMIN AUTHORIZED METHOD OF FLYING AN ARC IN IMC USING THE G1000. I can't download the G1000 manual right now, internet is too slow...but it is somewhere in that manual.
 
Let me know if you ever see it in the manual again. I've searched but no luck. It's a needle in a haystack for me.
 
KSCessnaDriver said:
Yeah basically. Kind of dumb, but such is life. I dealt with that on many occasions flying IFR.
Click to expand...

Having thought about this some more, I think that's remarkably silly. For a quarter million bucks I want a DME. :bandit:

Not only is it sufficient it is the ONLY GARMIN AUTHORIZED METHOD OF FLYING AN ARC IN IMC USING THE G1000. I can't download the G1000 manual right now, internet is too slow...but it is somewhere in that manual.
Click to expand...
Makes sense, you've got no other way to keep track of where you are.

Also, it's irrelevant...Martin State now has a RNAV approach :)

Sorry, but that's just plain nonsense
Click to expand...
I think my esteemed colleague means that no matter how much magic you have, you should always monitor raw data.
 
Autothrust Blue said:
Having thought about this some more, I think that's remarkably silly. For a quarter million bucks I want a DME. :bandit:
Click to expand...

I think I'd rather take the $8,000 (from the Diamond website, putting a KN63 in a DA40) plus it costs to put the DME in a G1000 and apply it to GPS database subscription and XM Radio/Weather subscriptions.
 
KSCessnaDriver said:
I think I'd rather take the $8,000 (from the Diamond website, putting a KN63 in a DA40) plus it costs to put the DME in a G1000 and apply it to GPS database subscription and XM Radio/Weather subscriptions.
Click to expand...

True. I'm not precisely in the market to buy a G1000-fitted airplane...I just operate 'em.
 
In the 121 environment, DME arcs are flown via the FMS providing lateral guidance around the arc ala G1000. This is also taught in the FAA approved training curriculum.

No 121 carrier is doing "turn 10, twist 10" in the mountains of mexico at night during an approach. At most companies you can't even dispatch to those types of airports with the FMS deferred.
 
ClearedToThe said:
In the 121 environment, DME arcs are flown via the FMS providing lateral guidance around the arc ala G1000. This is also taught in the FAA approved training curriculum.

No 121 carrier is doing "turn 10, twist 10" in the mountains of mexico at night during an approach. At most companies you can't even dispatch to those types of airports with the FMS deferred.
Click to expand...

No one said it is better to the "turn 10, twist 10" method, I am only pointing out discrepancies in what the books say. If it is in your ops specs or gps manual, you've got no problems. If not, I don't see a way to get around the FAA's wording.

If I remember correctly, a DME arc on a VOR approach that is in the database should be loaded with a VOR pointer and DME displayed in hold mode also. If it isn't in the database, a 10 nm (as needed) ring would be drawn for reference purposes only.
 
Pilot Hopeful said:
2) The referenced text DOES appear in the Instrument Procedures Handbook (IPH), as you noted.
Click to expand...
I incorrectly attributed the following text to the IPH: “Select from the airborne database the facility providing the DME arc as the active GPS WP. The only acceptable facility is the DME facility on which the arc is based. If this facility is not in your airborne database, you are not authorized to perform this operation." This text appears in the Instrument Flying Handbook (IFH), page 7-29.

Previously, I failed to note that this text appears after a note from the publisher: "The following provides guidance, which is not specific to any particular aircraft GPS system. For specific system guidance, refer to the POH/AFM, or supplement, or contact the system manufacturer" (IFH p. 7-29).

Appendix A of the IPH deals extensively with Airborne Navigation Databases. Note the following:
(1) ARINC 424 sets forth the air transport industry’s recommended standards for the preparation of airborne navigation system reference data tapes. (p. A-5)
(2) The data included in an airborne navigation database is organized into ARINC 424 records. These records are strings of characters that make up complex descriptions of each navigation entity. (p. A-5)
(3) Complex route records include those strings of fixes that describe complex flight paths. (p. A-7)
(4) The desire for RNAV equipment to have the ability to follow more complicated flight paths necessitated the development of the “Path/Terminator” field that is included in complex route records. There are currently 23 different Path/Terminators in the ARINC 424 standard. They enable RNAV systems to follow the complex paths that make up instrument departures, arrivals, and approaches. They describe to navigation avionics a path to be followed and the criteria that must be met before the path concludes and the next path begins. (p. A-7)
(5) RNAV (RNP) instrument approach procedures are now capable of precision curved flight tracks. (p. A-14)
(6) The constant radius arc RF leg defines a constant radius turn between two database fixes, lines tangent to the arc, and a center fix. While the arc initial point, arc ending point, and arc center point are available as database fixes, implementation of this leg type may not require the arc center point to be available as a fix. (p. A-15)

The Garmin G1000 Pilot’s Guide provides the following information:
"The G1000 supports all ARINC 424 leg types that have associated waypoint fixes. The G1000 uses the following leg types as part of the Jeppesen database (each of these legs is displayed on the active flight plan): AF - DME arc to a fix."

My interpretation of the above information is this: The IFH outlines GPS use on DME arcs as guidance only. The IPH overview of ARINC 424 sufficiently encompasses the DME arc capabilities of the Garmin 1000 and other compatible RNAV systems. If a given RNAV system includes ARINC 424-compliant GPS arc procedures, these procedures may be flown by retrieving them from the database. Selecting the DME facility as an active fix is unnecessary.

Is this information sufficient?
 
Pilot Hopeful said:
I incorrectly attributed the following text to the IPH: “Select from the airborne database the facility providing the DME arc as the active GPS WP. The only acceptable facility is the DME facility on which the arc is based. If this facility is not in your airborne database, you are not authorized to perform this operation." This text appears in the Instrument Flying Handbook (IFH), page 7-29.

Previously, I failed to note that this text appears after a note from the publisher: "The following provides guidance, which is not specific to any particular aircraft GPS system. For specific system guidance, refer to the POH/AFM, or supplement, or contact the system manufacturer" (IFH p. 7-29).

Appendix A of the IPH deals extensively with Airborne Navigation Databases. Note the following:
(1) ARINC 424 sets forth the air transport industry’s recommended standards for the preparation of airborne navigation system reference data tapes. (p. A-5)
(2) The data included in an airborne navigation database is organized into ARINC 424 records. These records are strings of characters that make up complex descriptions of each navigation entity. (p. A-5)
(3) Complex route records include those strings of fixes that describe complex flight paths. (p. A-7)
(4) The desire for RNAV equipment to have the ability to follow more complicated flight paths necessitated the development of the “Path/Terminator” field that is included in complex route records. There are currently 23 different Path/Terminators in the ARINC 424 standard. They enable RNAV systems to follow the complex paths that make up instrument departures, arrivals, and approaches. They describe to navigation avionics a path to be followed and the criteria that must be met before the path concludes and the next path begins. (p. A-7)
(5) RNAV (RNP) instrument approach procedures are now capable of precision curved flight tracks. (p. A-14)
(6) The constant radius arc RF leg defines a constant radius turn between two database fixes, lines tangent to the arc, and a center fix. While the arc initial point, arc ending point, and arc center point are available as database fixes, implementation of this leg type may not require the arc center point to be available as a fix. (p. A-15)

The Garmin G1000 Pilot’s Guide provides the following information:
"The G1000 supports all ARINC 424 leg types that have associated waypoint fixes. The G1000 uses the following leg types as part of the Jeppesen database (each of these legs is displayed on the active flight plan): AF - DME arc to a fix."

My interpretation of the above information is this: The IFH outlines GPS use on DME arcs as guidance only. The IPH overview of ARINC 424 sufficiently encompasses the DME arc capabilities of the Garmin 1000 and other compatible RNAV systems. If a given RNAV system includes ARINC 424-compliant GPS arc procedures, these procedures may be flown by retrieving them from the database. Selecting the DME facility as an active fix is unnecessary.

Is this information sufficient?
Click to expand...

That is good info. I'll do research tomorrow and see if it applies to the 430/530.
 
mattchew said:
Just read this article on AOPA, might find it to be useful in this thread. Sounds to me like either use (direct to fix OR loaded approach is legal, and DME arcs are legal)
http://www.aopa.org/whatsnew/air_traffic/gps_in_lieu.html
Click to expand...

I saw that earlier before I posted my question. It seemed to me that there was only one way to do it:

DME arcs associated with instrument approaches may be flown using GPS distance provided the DME transmitter, on which the arc is based, is identified in the GPS database
 
lhornaday said:
According to the Instrument Flying Handbook, 2009, page 7-29, the answer is no.

http://www.faa.gov/library/manuals/aviation/instrument_flying_handbook/media/FAA-H-8083-15A%20-%20Chapter%2007.pdf

To Fly a DME Arc:
1. Verify aircraft GPS system integrity monitoring
is functioning properly and indicates satisfactory
integrity.
2. Select from the airborne database the facility providing
the DME arc as the active GPS WP. The only
acceptable facility is the DME facility on which the arc
is based. If this facility is not in your airborne database,
you are not authorized to perform this operation.
3. Maintain position on the arc by reference to the GPS
distance instead of a DME readout.
Click to expand...

lhornaday said:
I saw that earlier before I posted my question. It seemed to me that there was only one way to do it:

DME arcs associated with instrument approaches may be flown using GPS distance provided the DME transmitter, on which the arc is based, is identified in the GPS database
Click to expand...

This is what I was thinking when I read the above earlier in the thread. I thought I was just being stupid and didn't say anything. Long live doing DME Arcs with an RMI Needle selected.
 
You must log in or register to reply here.
Back
Top